Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.
Phys Rev Lett. 2013 Jul 19;111(3):036402. doi: 10.1103/PhysRevLett.111.036402. Epub 2013 Jul 17.
We derive an exchange energy functional of generalized gradient form with a corresponding potential that changes discontinuously at integer particle numbers. The functional is semilocal, yet incorporates key features that are connected to the derivative discontinuity of Kohn-Sham density-functional theory. We validate our construction for several paradigm systems and explain how it addresses central well-known deficiencies of antecedent semilocal methods, i.e., the description of charge transfer, properly localized orbitals, and band gaps. We find, e.g., an improved shell structure for atoms, eigenvalues that more closely correspond to ionization energies, and an improved description of band structure where localized states are lowered in energy.
我们推导出了一种具有相应势的广义梯度形式的交换能泛函，该势在整数粒子数处不连续变化。该泛函是半局部的，但包含了与 Kohn-Sham 密度泛函理论的导数不连续性相关的关键特征。我们对几个范例系统进行了验证，并解释了它如何解决先前半局部方法的一些众所周知的缺陷，例如电荷转移、适当的局域轨道和能带隙的描述。例如，我们发现原子的壳层结构得到了改善，特征值与电离能更接近，能带结构的描述也得到了改善，其中局域态的能量降低。
